Apparatus for molding a container with offset parting line

Abstract

A mold assembly is provided for making a thermoplastic container having a bottom, side and unitary closure or top wall means with a parting line along a plane of symmetry in the bottom and sidewall means but with the parting line offset on the top wall means to define a generally flat, pierceable membrane on a major portion of the exterior surface of the top wall means. The mold assembly molds and seals the container from a tube of thermoplastic material, which assembly includes mold parts having lower sections adapted to open and close relative to a center parting plane to shape the bottom and sidewall means of the container and having a pair of upper sections adapted to shape the unitary closure. One of the upper sections has a removable protuberance for forming a major portion of the container top closure surface with the mold parting line thereon offset relative to the center parting plane of the mold assembly.

What is claimed is: 
     
       1. A mold assembly for molding a container from an extruded length of thermoplastic tubing and thereafter sealing the molded container, which assembly comprises: a pair of movable, opposed lower mold sections each having a principal mold face defining a cavity adapted to shape a body portion of the container and a pair of movable opposed upper mold sections each having a principal mold face and adapted to shape a unitary flat, pierceable closure for the container;   said movable mold sections being positionable between an open mold position and a closed mold position and being adapted to receive between said principal mold faces said extruded length of thermoplastic tubing, and the principal mold faces of the lower mold sections together defining a central parting plane when the lower mold sections are in said closed mold position; and   one of said pair of upper mold sections having a mold insert removably affixed on the principal mold face thereof for shaping at least a portion of said pierceable closure, said mold insert being a generally cylindrical member having a substantially flat base at one end adapted to shape a major portion of the exterior surface of said pierceable closure, and the other of said pair of upper mold sections having a recess complementary to said mold insert and adapted to mate with said mold insert when the upper mold sections are in said closed mold position;   whereby at least a portion of the resulting parting line on the closure of the molded container is displaced relative to said central parting plane by said removable mold insert.   
     
     
       2. The mold assembly in accordance with claim 1 wherein said base is of a generally circular configuration and has a diameter greater than the diameter of said cylindrical member. 
     
     
       3. In a mold assembly for molding and sealing a container from a tube of thermoplastic material, said container having a unitary, generally flat, syringe-pierceable, top closure surface; said mold assembly having a lower mold comprising first and second lower mold sections positionable relative to a central mold parting plane between an open mold position and a closed mold position for forming the container, said first and second lower mold sections defining a container mold cavity oriented generally symmetrically about said central mold parting plane when said first and second lower mold sections are in said closed position, the improvement which comprises: said mold assembly further including an upper mold comprising first and second upper mold sections positionable relative to said central mold parting plane between an open mold position and a closed mold position for forming the top closure surface of the container in a generally circular configuration;   part of said first upper mold section terminating short of said central mold parting plane to define a recess in the first upper mold section above said container mold cavity defined by said lower mold sections when the mold sections are in the closed position;   said second upper mold section having a removable protuberance extending beyond said central parting plane and projecting over the container mold cavity defined by the lower mold sections when the mold sections are in the closed position, said protuberance having a base for forming a major portion of the container top closure surface, said protuberance being adapted to confront and be received within said recess of said first upper mold section when said mold sections are in the closed position, said removable protuberance including a generally cylindrical upper member and a frustoconical lower member presenting a lower circular surface with a diameter greater than said cylindrical member; and   said upper mold sections presenting mold surfaces for defining the top of the container mold cavity for forming said container top closure surface with the mold parting line thereon offset relative to said central mold parting plane by said removable protuberance.   
     
     
       4. The improvement in accordance with claim 3 in which the longitudinal axis of said cylindrical upper member is spaced from and parallel with said central parting plane and wherein a portion thereof extends outwardly beyond the periphery of the top of said container mold cavity.